Meet the Beach Pea (Lathyrus japonicus), a native species with a surprising superpower: it helps stabilize our dunes and enrich the soil—all while thriving in one of the harshest environments around.
Often found growing beside Marram Grass (Ammophila breviligulata), the Beach Pea plays a key role in anchoring the sand against the forces of wind and waves. Together, these plants act as a natural barrier, protecting the coastline from erosion and helping dune systems recover after storms.
But the Beach Pea’s secret power lies underground. It forms a unique relationship with certain bacteria in the soil that allows it to fix nitrogen. This enriches the sandy beach soil, making it easier for other plants to grow.
To better understand this plant’s ecological value, here are some common questions—along with answers informed by recent research by the Biology Department at the University of New Brunswick (UNB), right here on our local shores.
What makes Beach Pea special?Beach Pea is one of the few plants that thrive in dry, salty, nutrient-poor dune soils. Its extensive underground root systems help anchor the sand, while its above-ground vines trap wind-blown sand and provide food and shelter for birds, small mammals, and pollinating insects. This makes it a key player in supporting the natural structure of the beach and dunes.
Beach pea grows alongside marram grass on the upper part of the beach and especially on the dune.
How does it help enrich the soil?Beach Pea has a symbiotic relationship with bacteria that live in small nodules on its roots. One of these bacteria is called Rhizobium leguminosarum. These helpful microbes convert nitrogen gas from the air into a form of nitrogen the plant can use—a process called nitrogen fixation. This not only allows Beach Pea to thrive in poor soil, but it also adds nitrogen back into the ground, benefiting other nearby plants..
The Beach Pea produces beautiful purple-pink flowers that attract pollinators. Beneath the surface, Rhizobia bacteria inhabit small growths, called nodules, on the plant’s roots.
Why is nitrogen important?Nitrogen is essential for plant growth but often lacking in dune soils. When Beach Pea adds nitrogen to the soil, it makes it easier for other native plants to take root, strengthening the entire dune system over time.
What does Beach Pea look like?Look for low, spreading green vines on the sand. In summer, it produces vibrant purple-pink flowers that attract pollinators. You’ll often find it growing alongside Marram Grass near the top of the beach and on the dunes.
What did the UNB study uncover?In 2024, UNB researchers studied Beach Pea populations at Aboiteau Beach to better understand the bacteria supporting its growth and to find ways to encourage their proliferation on dunes to prevent erosion.
A University of New Brunswick research team led by biologist Shawn MacLellan identified around 30 different species of bacteria living within Beach Pea roots—including the nitrogen-fixer Rhizobium leguminosarum. These microbial allies offer promising insights for strengthening dune stability across the region.
How can we help protect these plants?Respect areas where Beach Pea and other coastal plants grow. Walking on vegetation causes damage to fragile root systems and weakens the entire structure of the beach and dunes. Keep a distance from the upper part of the beach and dunes and always use designated beach access points - and encourage others to do the same.
Why does this matter?Dunes act as natural barriers that protect our communities against storm surges, sea-level rise, and coastal erosion—threats that are increasing with climate change. By supporting native species like Beach Pea and the research that helps us understand them, we’re helping to preserve the long-term health and resilience of our coastline.
So next time you visit the beach, take a closer look. That patch of vegetation quietly holding the sand in place might just be a Beach Pea, doing its part in safeguarding our shores.